System and method for combining the outputs of multiple, disparate types of power sources

ABSTRACT

A system for, and method of, combining the outputs of multiple, disparate types of power sources and an isolated converter module employed in the same. In one embodiment, the system includes: (1) a plurality of isolated converter modules having power inputs couplable to corresponding disparate types of power sources and a DC-output converter configured to convert power received from at least one of the power sources to DC power and (2) a DC bus coupled to power outputs of the plurality of isolated converter modules and configured to receive and aggregate the DC power. With such system, a universal converter module can be employed to identify and convert power from a variety of conventional and renewable power sources.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application Ser.No. 61/225,037, filed by Fontana, et al., on Jul. 13, 2009, entitled“Lineage Priority Source Power Center,” commonly assigned with thisapplication and incorporated herein by reference. This application isalso related to U.S. patent application Ser. No. 12/372,659, filed byJagota, et al., on Feb. 17, 2009, entitled “DC Plant Controller andMethod for Selecting Among Multiple Power Sources and DC Plant Employingthe Same,” commonly assigned with this application and incorporatedherein by reference.

TECHNICAL FIELD

This application is directed, in general, to power conversion and, morespecifically, to a system and method for combining the outputs ofmultiple, disparate types of power sources.

BACKGROUND

Telecommunication service providers are adding alternative (e.g.,“green”) power sources as options for powering evermore of theirtelecommunication sites, such as central offices and cell towers. Thisbrings real benefits in operating costs and commercial electric power“grid” independence, yet it also introduces a host of new, oftendisparate equipment to the network that the service providers mustmaintain and replace as years go by. As a consequence, the equipmentthreatens the sustainability of the network and its quality of service.The risk is particularly acute when the equipment is exposed to weatherand lightning, which is almost always the case.

Complicating matters, disparate types of power sources have differentpriorities of use. For example, renewable power sources, such as solarand wind power, should be preferred and therefore have a higher prioritythan fossil-fuel-powered backup generators and fee-based, and possiblyalso fossil-fuel-powered, commercial electric power. Being lower inpriority, the latter should only be used only as necessary. Because theyare typically reserved for emergency use, backup batteries may have thelowest priority.

SUMMARY

One aspect provides a system for combining the outputs of multiple,disparate types of power sources. In one embodiment, the systemincludes: (1) a plurality of isolated converter modules having powerinputs couplable to corresponding disparate types of power sources and aDC-output converter configured to convert power received from at leastone of the power sources to DC power and (2) a DC bus coupled to poweroutputs of the plurality of isolated converter modules and configured toreceive and aggregate the DC power.

Another aspect provides an isolated converter module. One embodiment ofthe module includes: (1) a power input, (2) a source recognition circuitcoupled to the power input and configured to receive a signal based onat least one characteristic of power received via the power input andrecognize a power source type based on the at least one characteristic,(3) a parameter selection circuit coupled to the priority determinationcircuit and configured to select operating parameters based on the powersource type, (4) a converter controller coupled to the parameterselection circuit and configured to provide drive signals in accordancewith the operating parameters, (5) a DC-output converter coupled to theconverter controller and configured to receive the drive signals andconvert the power to DC form and (6) a power output configured toreceive the power converted to the DC form from the DC-output converter.

Yet another aspect provides a method of combining the outputs ofmultiple, disparate types of power sources. One embodiment of the methodincludes: (1) recognizing the types of each of the multiple powersources, (2) selecting respective operating parameters based on thetypes, (3) converting power to DC form according to the convertercontroller parameters and (4) combining the power in the DC form in acommon DC bus.

Still another aspect provides a telecommunications rectifier. In oneembodiment, the rectifier includes: (1) a power input, (2) a convertercontroller configured to provide drive signals for converting powerreceived from either the commercial electric power grid or a renewablepower source, (3) a DC-output converter coupled to the power input andthe converter controller and configured to receive the drive signals andconvert the power to DC form and (4) a power output configured toreceive the power converted to the DC form from the DC-output converter.

BRIEF DESCRIPTION

Reference is now made to the following descriptions taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a high-level block diagram of one embodiment of a system forcombining the outputs of multiple, disparate types of power sources;

FIG. 2 is an elevational view of one embodiment of an equipment rackcontaining multiple shelves and capable of containing a system forcombining the outputs of multiple, disparate types of power sources;

FIG. 3 is a block diagram of one embodiment of an isolated convertermodule of the system of FIG. 1; and

FIG. 4 is a flow diagram of one embodiment of a method of combining theoutputs of multiple, disparate types of power sources.

DETAILED DESCRIPTION

To date, suppliers of alternative energy equipment have used distributedgeneration (DG), colloquially known as “grid-tying,” to incorporatealternative power sources. DG involves coupling alternative powersources to the commercial alternating current (AC) power grid such thatthe sources can synchronize with, and supply power to, the grid. Thegrid then supplies any and all loads, including the telecommunicationequipment. Unfortunately, grid-tying incurs both AC conversioninefficiencies and the risk of propagating transient high voltage(“spikes”) resulting from lightning. For these reasons, serviceproviders have resisted grid-tying.

Described herein are various embodiments of a system and method thatemploy standard power conversion modules to form a redundant,fault-tolerant system that can aggregate power from various, disparate,often both alternative and conventional, power sources while maintainingsufficient isolation to resist faults emanating from a particular powersource. Power from the various sources is converted to direct current(DC) of appropriate voltage and then aggregated. Thereafter, the DC maybe used to power DC loads or converted to AC, after which it may be usedto power AC loads. In a telecommunication environment, these loads mayinclude backup batteries and telecommunication equipment.

The system and method call for the power sources to be galvanicallyisolated from one another to frustrate fault propagation. Variousembodiments of the system and method employ transformers in theconverters to provide isolation; a magnetic field transfers power whileproviding isolation. Those skilled in the art understand other circuitsthat can be employed to provide isolation. Various embodiments of thesystem and method employ diodes to aggregate power from the varioussources in a straightforward manner. Those skilled in the art understandthat other devices and circuits can be employed to aggregate the power.

Certain embodiments of the system and method address the issues of spareparts stocking (“sparing”) and network sustainability (“uptime”) byemploying uniform converter modules, which may be synonymously regardedas “identical,” “universal” or “generic,” that are configured to adaptthemselves to convert power received from different types of powersources. A single type of converter module can be used to convert powerfrom multiple source types, e.g., solar, wind, water, geothermal,commercial grid, emergency generator or backup battery. A serviceprovider need only stock the single converter type to ensure converterspare availability for any source.

Certain other embodiments also address concerns that alternative powersources could put essential network functions at risk by accommodatingpriority operation, namely preferentially employing alternative powersources but ensuring that more conventional and perhaps reliable powersources are available to be employed if or when the alternative powersources are interrupted. In some of the embodiments described in detailherein, isolated converter modules are configured to recognize the typeof power source from which they are receiving power, determine thepriority that the type of power source should have, select parametersaccording to which the power received from the power source is convertedand then convert that power to DC in accordance with the parameters.

Still other embodiments are capable of operating at an increasedefficiency by selectively turning off isolated converter modules whenmultiple such modules are coupled to an alternative power source andfewer than all such modules are capable of supplying the power receivedfrom the alternative power source. Further embodiments are capable ofemploying power factor correction to receive power from alternativepower sources at optimally efficient output voltages for thosealternative power sources and convert the power at optimally efficientDC-output converter input voltages.

FIG. 1 is a high-level block diagram of one embodiment of a system 100for combining the outputs of multiple, disparate types of power sources.The embodiment illustrated in FIG. 1 takes the form of a rack-mountedassemblage of modular equipment. Accordingly, the system 100 isillustrated as including a plurality of isolated converter modules 101a, 101 b, 101 c, . . . , 101 n. A DC bus 102 couples the outputs of theplurality of isolated converter modules 101 a, 101 b, 101 c, . . . , 101n together and provides a DC output 103, as FIG. 1 indicates, suitablefor powering a DC load 120. In one embodiment, a DC-DC converter may beemployed to power a DC load that requires a voltage differing from thatprovided by the DC bus 102. For applications that would benefit from anAC output, the DC bus 102 may be coupled to an inverter 104 (a DC-ACconverter), which provides an AC output 105, as FIG. 1 indicates,suitable for powering an AC load 130.

The plurality of isolated converter modules 101 a, 101 b, 101 c, . . . ,101 n receive power from a corresponding plurality of power sources 110a, 110 b, 110 c, . . . , 110 n. Because various embodiments isconfigured to determine relative priorities of the power sources 110 a,110 b, 110 c, . . . , 110 n, the power sources 110 a, 110 b, 110 c arelabeled priority power sources, indicating that they have (typicallydiffering) priorities higher than a lowest priority, and the powersource 110 n is labeled a fallback power source, indicating that it hasthe lowest priority. In the illustrated embodiment, the priority powersource 1 110 a is a solar-derived power source (e.g., a solar panel),the priority power source 2 110 b is a wind-derived power source (e.g.,a turbine-driven generator), the priority power source 3 110 c is thecommercial electric power grid (which may also be regarded as a firstbackup power source), and the fallback power source 110 n is a backuppower source (e.g., one or more fuel cells, one or more batteries or oneor more strings of batteries). If the backup power source is one or morefuel cells, one or more batteries or one or more strings of batteries,it may be coupled directly to the DC bus 102 (as a broken line couplingthe fallback power source 110 n and the DC bus 102 indicates) orisolated by a charger (not shown) that draws its power from the DC bus102 or any of the other power sources 110 a, 110 b, 110 c, . . . .

As will be described in greater detail in conjunction with FIG. 2 below,each of the plurality of isolated converter modules 101 a, 101 b, 101 c,. . . , 101 n is capable of operating independently of the others.However, the embodiment illustrated in FIG. 1 employs a system oversightcontroller 106 configured to monitor and supervise the plurality ofisolated converter modules 101 a, 101 b, 101 c, . . . , 101 n to ensurethat they are cooperating properly and constructively with respect toone another. An oversight bus 107 couples the system oversightcontroller 106 to each of the plurality of isolated converter modules101 a, 101 b, 101 c, . . . , 101 n. In performing its functions, thesystem oversight controller 106 may make decisions based on inputsignals received from the plurality of isolated converter modules 101 a,101 b, 101 c, . . . , 101 n via the oversight bus 107 and one or morecharacteristics of the DC bus 102, e.g., sensed at a control point 108.The one or more characteristics may include voltage, current or anyother desired characteristic.

Turning briefly to FIG. 2, illustrated is an elevational view of oneembodiment of an equipment rack 200 containing multiple shelves andcapable of containing a system for combining the outputs of multiple,disparate types of power sources. The rack 200 may be, for example, astandard equipment rack in a conventional battery plant (e.g., as may belocated in a telecommunication facility such as a central office, orCO). FIG. 2 illustrates a plurality of shelves 210 a, 210 b, 210 c, . .. , 210 n configured to support one or more isolated converter modules101 a, 101 b, 101 c, . . . , 101 n. In the illustrated embodiment, theisolated converter modules 101 a, 101 b, 101 c, . . . , 101 n on a givenshelf 210 a, 210 b, 210 c, . . . , 210 n are dedicated to a particulartype of power source. For example, the isolated converter modules 101 aon the shelf 210 a may be dedicated to converting power received fromone or more wind-driven energy sources, and the isolated convertermodules 101 n on the shelf 210 n may be dedicated to converting powerreceived from one or more backup batteries or battery strings. In onespecific embodiment, separate isolated converter modules 101 a areemployed to convert each phase of a single wind-driven energy source. Inanother embodiment, a single isolated converter module 101 a is employedto convert power received from multiple wind-driven energy sources.Those skilled in the art will understand that the isolated convertermodules 101 a, 101 b, 101 c, . . . , 101 n may be arranged in anymanner, however.

Each shelf 210 a, 210 b, 210 c, . . . , 210 n may support one or morespare isolated converter modules, 101 a, 101 b, 101 c, . . . , 101 nthat are either wholly disconnected from the remainder of the system,connected to the remainder of the system and placed on standby orconnected to the remainder of the system and operating at less than fulloutput current. The latter two configurations are colloquially regardedas “hot-swappable.” In a system having a “hot-swappable” module, one ormore standby converter modules may be substituted for one or moremalfunctioning converter modules automatically, and without requiringhuman knowledge or intervention. In the illustrated embodiment, thesystem oversight controller 106 may command this substitution, typicallybased at least in part on signals received from any malfunctioningconverter modules. As described below in conjunction with FIG. 3, theisolated converter modules 101 a, 101 b, 101 c, . . . , 101 n mayperform power factor and voltage adjustments to increase the powerreceived from a power source and optimize conversion efficiency.

Inherent in the latter two configurations described above is the abilityto perform “N+1 sparing” or, more generally, “N+M sparing,” where N=1 ora greater integer. For example, N+1 isolated converter modules may beused for converting power from a given power source, when only Nisolated converter modules are required to convert the power. Under N+1sparing, each isolated converter module converts 1/(N+1)^(th) of thepower received from the power source. If one isolated converter modulemalfunctions, each of the remaining N isolated converter modules thenconverts 1/N^(th) of the power. N+M sparing would call for M isolatedconverter modules in excess of the N required to convert the power.

FIG. 2 also shows one embodiment of the system oversight controller 106,which happens to be located over the shelves 210 a, 210 b, 210 c, . . ., 210 n in the illustrated embodiment. Although FIG. 2 does not showthem, a DC bus and an oversight bus couple the various isolatedconverter modules 101 a, 101 b, 101 c, . . . , 101 n and the systemoversight controller 106 together as indicated above. In the illustratedembodiment, the DC and oversight buses run along a rear surface of therack 200 and include backplane connectors that allow the isolatedconverter modules 101 a, 101 b, 101 c, . . . , 101 n and perhaps thesystem oversight controller 106 to be plugged into them as they areinserted into the rack 200.

As described above, the illustrated embodiment of each of the pluralityof isolated converter modules 101 a, 101 b, 101 c, . . . , 101 n ofFIGS. 1 and 2 is configured to recognize the type of power source fromwhich they are receiving power, determine the priority that the type ofpower source should have, select parameters according to which the powerreceived from the power source is converted and then convert that powerto DC in accordance with the parameters. Thus, various embodiments ofone of the isolated converter modules 101 a, 101 b, 101 c, . . . , 101 nwill now be described.

FIG. 3 is a block diagram of one embodiment of an isolated convertermodule 300 of the system of FIG. 1. The illustrated embodiment of themodule 300 is embodied in a plurality of circuits mounted on a circuitboard 301 and, in some embodiments, encased in a protective shell 302.In various embodiments, the module 300 features backplane connectors(not shown, since FIG. 3 shows the module 300 in conceptual, rather thanphysical, form) that allow the module to be inserted into the rack 200of FIG. 2 and be coupled to the backplane thereof. Typically, thebackplane connectors would provide for most, if not all, of theelectrical connections that need to be made with the module 300.

The module 300 may also include one or more status indicators (e.g.,lights) on a front edge thereof (not shown) to indicate, among otherthings, the operating status of the module 300. In some embodiments, thedimensions of the protective shell and the placement of the backplaneconnectors are standardized that the modules are uniform and may beplugged into any one of a plurality of uniformly sized slots in a rack(e.g., the rack 200 of FIG. 2).

The module 310 includes a power input 310 configured to receive powerfrom a power source and a power output that leads to the DC bus 102. Asource recognition circuit 320 receives, from a control point 330, asignal based on at least one characteristic of the power received viathe power input 310. The at least one characteristic may be one or moreof a voltage, a current, a frequency, a phase, a DC offset, animpedance, a power factor, a harmonic content or any othercharacteristic of interest. In the illustrated embodiment, thecharacteristic is voltage. The source recognition circuit 320 isconfigured to identify the type of the power source based on thecharacteristic.

For example, a voltage signal having a relatively constant 50 or 60 Hzfrequency indicates that the power source is either afossil-fuel-powered AC backup generator or the commercial electric powergrid. By monitoring the voltage signal over a substantial period oftime, interruptions or substantial frequency variations may occur bywhich it can be inferred whether the power source is afossil-fuel-powered AC backup generator or the commercial electric powergrid.

As another example, a voltage signal exhibiting significant frequencyvariations over time and often exceeding 60 Hz indicates an ACwind-driven power source. A low-frequency (e.g., less than 1 Hz) or DCvoltage indicates that the power source is either a solar panel, afossil-fuel-powered DC backup generator or a DC wind-driven powersource. By monitoring the voltage signal over a substantial period oftime (e.g., over a day and a night), interruptions or voltage variationsmay occur by which it can be inferred whether the power source is asolar panel, a fossil-fuel-powered DC backup generator or a DCwind-driven power source. Based on the characteristic, perhaps sensedover time, the source recognition circuit 320 is configured to recognizethe type of the power source and provides a signal indicating the type.

The illustrated embodiment of the module 300 is configured for use insystems in which disparate types of power sources have priorities.Accordingly, a priority determination circuit 340 is coupled to thesource recognition circuit 320. The priority determination circuit 340is configured to receive the signal from the source recognition circuit320 that indicates the type of the power source and determine a prioritythat the power source should have based on the signal. As stated above,power derived renewable energy sources are likely to have a higherpriority than emergency power, power derived from fossil fuel or powerthat needs to be purchased (i.e., the commercial electric power grid).The priority determination circuit 340 is further configured to providea signal indicating the priority.

In the illustrated embodiment, priority is carried out by assigningnominal relative output voltages to the DC-output converters. In theillustrated embodiment, power from disparate sources is combined in a DCbus using diodes coupled to the outputs of the power converterscorresponding to each source. In this embodiment, power sources areprioritized in the relative converter output voltages. A converterassigned a higher output voltage naturally causes that converter tosupply more power to the DC bus 102 than another converter having alower output voltage.

For example, if the DC bus 102 is nominally a 48 V bus, a firstconverter may be assigned to operate in a range around a nominal 48.1 Voutput voltage, a second converter may be assigned to operate in a rangearound a nominal 48.0 V output voltage, and a third converter may beassigned to operate in a range around a nominal 47.9 V output voltage.In this example, the first converter will naturally provide power to theDC bus 102 until it either reaches its current limit and output voltagebegins to decrease. When the output voltage of the first converterreaches 48.0 V, the second converter will likely begin to contributepower to the DC bus 102. Likewise, the first and second converters willshare the burden of providing power to the DC bus 102 until their outputvoltages decrease to 47.9 V, at which point the third converter willlikely begin to contribute its power to the DC bus 102 as well. Thoseskilled in the art will understand that if any of the power sources isinterrupted outright, its corresponding converter will stop contributingpower to the DC bus 102, and other converters will make up for the lostpower. In a well-designed system, the converter having the lowest outputvoltage (i.e., the lowest priority) is assumed always to be available toprovide power to the DC bus 102.

The above example illustrates a type of maximum power point tracking(MPPT), recognizing that sustainable power sources typically have alimited source impedance that varies with time. The power drawn fromthem should therefore be carefully managed to be maximized. For thisreason, various embodiments of the converters are configured torecognize the nature of the source and adjust the power drawn from thesource continually over time to extract energy with relatively low powerloss. When power is available from one or more renewable sources, thoseconverters connected to the renewable sources adjust their outputcurrent to provide a larger fraction of the total power being deliveredto the load. MPPT can be used to advantage with respect to renewablesources, allowing output voltage to be adjusted continually to keep thepower drawn from one or more renewable sources at or near their maximum.For this reason, continual (time-varying) adjustment of output currentbased on availability of the renewable source can be important.

A parameter selection circuit 350 is coupled to the prioritydetermination circuit 340. The parameter selection circuit 350 isconfigured to select operating parameters appropriate for convertingpower received at the power input 310 to a form appropriate for the DCbus 102 (i.e., based on the type recognized by the source recognitioncircuit 320). In the illustrated embodiment, the parameter selectioncircuit 350 also selects operating parameters based on the prioritydetermined by the priority determination circuit 340. For example, ifthe source recognition circuit 320 determines that the input power is DCpower provided by a solar panel, the parameter selection circuit selectsoperating parameters appropriate for DC-DC conversion. Further, becausesolar energy typically has a relatively high priority, the operatingparameters are likely to call for the module 300 to have a higher outputvoltage.

In an alternative embodiment, priority is carried out by settingrelative current limit points of the DC-output converters. Those skilledin the pertinent art are familiar with current limit control and howcurrent limit control can be carried out to effect load sharing and, byextension, priority. Those skilled in the pertinent art will alsounderstand that other techniques may be employed to establish loadsharing and priority.

A converter controller 360 is coupled to the parameter selection circuit350. The converter controller 360 is configured to provide drive signalsto an isolated DC-output converter 370 in accordance with the operatingparameters provided by the parameter selection circuit 350. Theconverter controller 360 typically receives signals (e.g., voltage,current or temperature signals) back from the isolated DC-outputconverter 370 that allow it to adapt its control to accommodate changingcircumstances (e.g., changes in input or output voltage or current).Those skilled in the art are familiar with various converter topologiescapable of converting DC or AC input power to DC form. Therefore, theoperation of the isolated DC-output converter 370 will not be furtherdescribed herein. It should also be noted that the converter controller360 is coupled to the oversight bus 107. This allows the convertercontroller 360 to provide signals indicating its status and/or operationto the system oversight controller 106 of FIG. 1 and/or receive commandsignals from the system oversight controller 106 that can alter theoperation of the converter controller 360.

Many of the above-described circuits may be embodied as discrete orintegrated circuits (“hardware”) or as a sequence of instructions(“software” or “firmware”) executable on a general-purpose processor tocarry out desired functions. The scope of the invention includes allsuch embodiments.

As stated above, the modules in a given system galvanically isolate thedisparate types of power sources from one another and the DC bus.Accordingly, the module 300 provides galvanic isolation. In theillustrated embodiment, the isolated DC-output converter 370 providesisolation in the form of a transformer (not shown) having distinctprimary and secondary windings, forcing power transfer to occur via thetransformer's magnetic field. In alternative embodiments, isolation isprovided outside of the converter 370 and/or by conventional orlater-developed galvanic isolation techniques other than magneticfield-based techniques.

In the illustrated embodiment, the DC-output converter 370 includes aDC-DC resonant stage (not shown) coupled to a secondary winding of thetransformer. The DC-DC resonant stage is configured to employzero-voltage switching to minimize switching stress and powerdissipation. The illustrated embodiment of the DC-output converter 370also includes a boost stage (not shown) coupled to a primary winding ofthe transformer. The boost stage is configured to adjust a power factorof the power and accommodate any voltage difference that may existbetween an operating voltage of a renewable power source coupled to thepower input 310 and the optimum input voltage of the DC-DC resonantstage. Those skilled in the art are familiar with DC-DC resonant stages,zero-voltage switching, boost stages and power factor adjustment. Ageneral discussion of these will therefore not be undertaken herein.

As stated above, the illustrated embodiment of the system employs diodesto combine the power from the disparate sources. In the illustratedembodiment, each module 300 in a given system incorporates a diode forthat purpose. Accordingly, FIG. 3 shows a forward-biased diode 390coupled to the output of the isolated DC-output converter 370. The diode390 is forward-biased to attenuate substantial currents before they canenter the module 300 from the DC bus 102. This not only substantiallyprevents one converter module from providing power to another convertermodule, but at least partially prevents fault currents (e.g., transientsresulting from lightning strikes) from propagating into the module 300and further at least partially prevents a malfunctioning module fromdraining power from the DC bus 102.

Alternative embodiments employ a relay, a field-effect transistor (FET)or other type of controllable switch to combine the power from thedisparate sources. Those skilled in the pertinent art understand thatvarious conventional and later-developed devices or circuits may beemployed to combine the power from the disparate sources and thereforefall within the broad scope of the invention.

Turning back to FIG. 1, the operation of the illustrated embodiment ofthe system oversight controller 106 can now be described more fully. Asstated above, the illustrated embodiment of the system oversightcontroller 106 may be capable of determining when a particular convertermodule is malfunctioning and, in some embodiments, substituting anothermodule for the malfunctioning module. In various embodiments, the systemoversight controller 106 is also configured to monitor the DC bus 102 toregulate its voltage. In certain other embodiments, the system oversightcontroller 106 is configured to monitor the isolated converter modules101 a, 101 b, 101 c, . . . , 101 n to ensure that they are not exceedingtheir current limits or operating at excessive temperatures. The systemoversight controller 106 may also be configured to monitor the isolatedconverter modules 101 a, 101 b, 101 c, . . . , 101 n to determinewhether or not the priorities are proper. The system oversightcontroller 106 may alternatively or further be configured to generateoperating logs and/or maintenance or warning signals indicatingconditions that need attention. The system oversight controller 106 mayprovide the operating logs and/or maintenance or warning signals via anetwork connection for remote storage or receipt. Those skilled in thepertinent art will understand that the system oversight controller 106may be employed to perform alternative or additional functions fromwhich a particular application or installation may benefit.

FIG. 4 is a flow diagram of one embodiment of a method of combining theoutputs of multiple, disparate types of power sources. The method beginsin a start step 410. In a step 420, types of each of multiple powersources is recognized. In a step 430, priorities for the power sourcesare determined. In a step 440, operating parameters are selected forDC-output converters corresponding to the power sources. In oneembodiment, at least some of the operating parameters are based on thepriorities for the corresponding power sources. In a step 450, theDC-output converters operate to convert power to DC form according tothe converter controller parameters. In a step 460, the converted poweris combined in a common DC bus. In a step 470, oversight is provided tothe system. In a step 480, power is provided from the common DC bus to aload. DC power may be provided (1) directly to a DC load, (2) through aDC-DC converter to the DC load, or (3) through an inverter to an ACload. The method ends in an end step 490.

Those skilled in the art to which this application relates willappreciate that other and further additions, deletions, substitutionsand modifications may be made to the described embodiments.

1. A system for combining the outputs of multiple, disparate types ofpower sources, comprising: a plurality of isolated converter moduleshaving power inputs couplable to corresponding disparate types of powersources and a DC-output converter configured to convert power receivedfrom at least one of said power sources to DC power; and a DC buscoupled to power outputs of said plurality of isolated converter modulesand configured to receive and aggregate said DC power.
 2. The system asrecited in claim 1 wherein at least one of said plurality of isolatedconverter modules is configured to recognize a type of power sourcebased on a characteristic of power received therefrom, select operatingparameters according to which said power is to be converted and thenconvert said power to DC in accordance with said operating parameters.3. The system as recited in claim 2 wherein at least one of saidplurality of isolated converter modules is further configured todetermine a priority that said type of power source is to have andselect at least one of said operating parameters based on said priority.4. The system as recited in claim 1 wherein at least some of saidplurality of isolated converter modules are identical.
 5. The system asrecited in claim 1 further comprising a system oversight controllercoupled to said plurality of isolated converter modules and configuredto monitor and supervise said plurality of isolated converter modules.6. The system as recited in claim 5 wherein said system oversightcontroller is further configured to detect when one of said plurality ofisolated converter modules is malfunctioning and automaticallysubstitute a standby converter module therefor.
 7. The system as recitedin claim 1 further comprising a rack having shelves configured tosupport said plurality of isolated converter modules.
 8. The system asrecited in claim 1 wherein each of said plurality of isolated convertermodules has a diode coupled between said DC-output converter and a poweroutput of said each of said plurality of isolated converter modules. 9.An isolated converter module, comprising: a power input; a sourcerecognition circuit coupled to said power input and configured toreceive a signal based on at least one characteristic of power receivedvia said power input and recognize a power source type based on said atleast one characteristic; a parameter selection circuit coupled to saidpriority determination circuit and configured to select operatingparameters based on said power source type; a converter controllercoupled to said parameter selection circuit and configured to providedrive signals in accordance with said operating parameters; a DC-outputconverter coupled to said converter controller and configured to receivesaid drive signals and convert said power to DC form; and a power outputconfigured to receive said power converted to said DC form from saidDC-output converter.
 10. The isolated converter module as recited inclaim 9 further comprising a priority determination circuit coupled tosaid source recognition circuit and said parameter selection circuit andconfigured to determine a priority that a power source corresponding tosaid power received via said power input should have, said parameterselection circuit further configured to select at least one of saidoperating parameters based on said priority.
 11. The isolated convertermodule as recited in claim 9 wherein said at least one of said operatingparameters includes an output voltage of said DC-output converter. 12.The isolated converter module as recited in claim 9 wherein said atleast one characteristic is selected from the group consisting of: avoltage, a current, a frequency, a phase, a DC offset, an impedance, apower factor, and a harmonic content.
 13. The isolated converter moduleas recited in claim 9 wherein a transformer in said DC-output converteris configured to provide galvanic isolation therein.
 14. The isolatedconverter module as recited in claim 9 further comprising aforward-biased diode coupled between said DC-output converter and saidpower output.
 15. The isolated converter module as recited in claim 9wherein said converter controller has an interface configured to becoupled to an oversight bus.
 16. A method of combining the outputs ofmultiple, disparate types of power sources, comprising: recognizing saidtypes of each of said multiple power sources; selecting respectiveoperating parameters based on said types; converting power to DC formaccording to said converter controller parameters; and combining saidpower in said DC form in a common DC bus.
 17. The method as recited inclaim 16 further comprising determining priorities that said each ofsaid power sources should have, said selecting comprising selecting atleast some of said operating parameters based on said priorities. 18.The method as recited in claim 16 wherein said converting comprisesemploying transformer-isolated DC-output converters.
 19. The method asrecited in claim 18 wherein at least some of said plurality oftransformer-isolated DC-output converters are identical.
 20. The methodas recited in claim 16 further comprising at least one of: providingsaid converted power in DC form directly to a DC load, providing saidconverted power in DC form through a DC-DC converter to said DC load,and providing said converted power in DC form through an inverter to anAC load.
 21. The method as recited in claim 16 wherein said combiningcomprises employing forward-biased diodes.
 22. The method as recited inclaim 16 further comprising automatically: detecting a malfunctioningconverter; and substituting a standby converter therefor.
 23. Atelecommunications rectifier, comprising: a power input; a convertercontroller configured to provide drive signals for converting powerreceived from either the commercial electric power grid or a renewablepower source; a DC-output converter coupled to said power input and saidconverter controller and configured to receive said drive signals andconvert said power to DC form; and a power output configured to receivesaid power converted to said DC form from said DC-output converter. 24.The telecommunications rectifier as recited in claim 23 furthercomprising a source recognition circuit coupled to said power input andsaid converter controller and configured to recognize whether said poweris received from said commercial electric power grid or a renewablepower source based on at least one characteristic of said power.
 25. Thetelecommunications rectifier as recited in claim 23 wherein saidrectifier is contained in a module that is mountable in a standardequipment rack of a battery plant.
 26. The telecommunications rectifieras recited in claim 23 further comprising a priority determinationcircuit coupled to said converter controller and configured to determinea priority that a power source corresponding to said power received viasaid power input should have.
 27. The telecommunications rectifier asrecited in claim 26 wherein said priority determines an output voltageof said DC-output converter.
 28. The telecommunications rectifier asrecited in claim 23 wherein said DC-output converter includes: anisolated DC-DC resonant stage configured to employ zero-voltageswitching; and a boost stage configured to adjust a power factor of saidpower and accommodate a voltage difference between an operating voltageof said renewable power source and an optimum input voltage of saidisolated DC-DC resonant stage.
 29. The telecommunications rectifier asrecited in claim 23 wherein said converter controller is configured toreceive a signal from a system oversight controller and shut down saidDC-output converter when multiple rectifiers are coupled to a singlerenewable power source and said system oversight controller determinesthat fewer rectifiers can convert power produced by said renewable powersource more efficiently.